We intend to study drug effects on ixodid tick salivary gland adenylate cyclase activity, characterization of the receptor of the adenylate cyclase complex, elucidation of the role of guanine nucleotides in adenylate cyclase activation, and effects of tick feeding on adenylate cyclase activity. We propose to identify cyclic AMP-dependent phosphorylation of specific proteins in isolated plasma membranes and monitor changes in the extent of phosphorylation during the fluid secretory process. We will determine possible membrane bound cyclic nucleotide phosphodiesterase (PDE) activity, and if time permits, the activity of gland cyclic GMP-hydrolyzing phosphodiesterase.